Unless you've been riding through the desert on a horse with no name, you'll know Johnny Depp is playing Tonto, in an update of The Lone Ranger. Cue debates about political correctness and analysis of Depp's ancestry (he's apparently one quarter Cherokee; is that enough?). But the real question is: who will play the Ranger himself? Or rather, who would want to?

Having Depp call you "kemosabe" is a poisoned chalice. Remember Orlando Bloom? No, really try. He was the ostensible hero of Pirates of the Caribbean, until Depp came along with his raffish Keith Richards shtick and took the franchise by the helm. Depp is rumoured to be earning $56m for the fourth instalment; Bloom's not even in it.

Depp must sometimes feel like Bette Davis in All About Eve, at the top of his game, ever-vulnerable to usurpers. Perhaps the best way to stay on top is to play second fiddle.

So who will King Johnny model himself on this time? He surely won't play Tonto as Jay Silverheels did in the 1950s TV series: noble, virtuous, but subservient and incapable of mastering English – an unpaid ethnic servant. Depp could try for a wise Native American who chides the feckless white man, except he's done that. It was called Dead Man, and Depp played the white guy.

A final word of caution: Silverheels went on to found a Native American acting workshop after the series ended; Clayton Moore, television's original Lone Ranger, barely acted again. But he regularly wore his black mask for public appearances, and when the show's owners issued a court order in 1979 to make him stop, he had his sunglasses made in the same shape until the studio relented. "I guess when I go up to the big ranch in the sky, I'll still have it on," he said. What actor would be desperate enough to don this cursed mask now? Have they tried Orlando Bloom?

• This article was amended on 2 December 2010, to clarify further that Clayton Moore's "original" status is as the first Lone Ranger on television (as opposed to in other media).